﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ManagedLzma.LZMA.Master
{
    partial class LZMA
    {
        /*
        RAM requirements for LZMA:
          for compression:   (dictSize * 11.5 + 6 MB) + state_size
          for decompression: dictSize + state_size
            state_size = (4 + (1.5 << (lc + lp))) KB
            by default (lc=3, lp=0), state_size = 16 KB.

        LZMA properties (5 bytes) format
            Offset Size  Description
              0     1    lc, lp and pb in encoded form.
              1     4    dictSize (little endian).
        */

        /*
        LzmaCompress
        ------------

        outPropsSize -
             In:  the pointer to the size of outProps buffer; *outPropsSize = LZMA_PROPS_SIZE = 5.
             Out: the pointer to the size of written properties in outProps buffer; *outPropsSize = LZMA_PROPS_SIZE = 5.

          LZMA Encoder will use defult values for any parameter, if it is
          -1  for any from: level, loc, lp, pb, fb, numThreads
           0  for dictSize
  
        level - compression level: 0 <= level <= 9;

          level dictSize algo  fb
            0:    16 KB   0    32
            1:    64 KB   0    32
            2:   256 KB   0    32
            3:     1 MB   0    32
            4:     4 MB   0    32
            5:    16 MB   1    32
            6:    32 MB   1    32
            7+:   64 MB   1    64
 
          The default value for "level" is 5.

          algo = 0 means fast method
          algo = 1 means normal method

        dictSize - The dictionary size in bytes. The maximum value is
                128 MB = (1 << 27) bytes for 32-bit version
                  1 GB = (1 << 30) bytes for 64-bit version
             The default value is 16 MB = (1 << 24) bytes.
             It's recommended to use the dictionary that is larger than 4 KB and
             that can be calculated as (1 << N) or (3 << N) sizes.

        lc - The number of literal context bits (high bits of previous literal).
             It can be in the range from 0 to 8. The default value is 3.
             Sometimes lc=4 gives the gain for big files.

        lp - The number of literal pos bits (low bits of current position for literals).
             It can be in the range from 0 to 4. The default value is 0.
             The lp switch is intended for periodical data when the period is equal to 2^lp.
             For example, for 32-bit (4 bytes) periodical data you can use lp=2. Often it's
             better to set lc=0, if you change lp switch.

        pb - The number of pos bits (low bits of current position).
             It can be in the range from 0 to 4. The default value is 2.
             The pb switch is intended for periodical data when the period is equal 2^pb.

        fb - Word size (the number of fast bytes).
             It can be in the range from 5 to 273. The default value is 32.
             Usually, a big number gives a little bit better compression ratio and
             slower compression process.

        numThreads - The number of thereads. 1 or 2. The default value is 2.
             Fast mode (algo = 0) can use only 1 thread.

        Out:
          destLen  - processed output size
        Returns:
          SZ_OK               - OK
          SZ_ERROR_MEM        - Memory allocation error
          SZ_ERROR_PARAM      - Incorrect paramater
          SZ_ERROR_OUTPUT_EOF - output buffer overflow
          SZ_ERROR_THREAD     - errors in multithreading functions (only for Mt version)
        */

        public static SRes LzmaCompress(
            P<byte> dest, ref long destLen,
            P<byte> src, long srcLen,
            P<byte> outProps, ref long outPropsSize, /* *outPropsSize must be = 5 */
            int level,      /* 0 <= level <= 9, default = 5 */
            uint dictSize,  /* default = (1 << 24) */
            int lc,        /* 0 <= lc <= 8, default = 3  */
            int lp,        /* 0 <= lp <= 4, default = 0  */
            int pb,        /* 0 <= pb <= 4, default = 2  */
            int fb,        /* 5 <= fb <= 273, default = 32 */
            int numThreads) /* 1 or 2, default = 2 */
        {
            CLzmaEncProps props = CLzmaEncProps.LzmaEncProps_Init();
            props.mLevel = level;
            props.mDictSize = dictSize;
            props.mLC = lc;
            props.mLP = lp;
            props.mPB = pb;
            props.mFB = fb;
            props.mNumThreads = numThreads;

            return LzmaEncode(dest, ref destLen, src, srcLen, props, outProps, ref outPropsSize, false, null, ISzAlloc.SmallAlloc, ISzAlloc.BigAlloc);
        }

        /*
        LzmaUncompress
        --------------
        In:
          dest     - output data
          destLen  - output data size
          src      - input data
          srcLen   - input data size
        Out:
          destLen  - processed output size
          srcLen   - processed input size
        Returns:
          SZ_OK                - OK
          SZ_ERROR_DATA        - Data error
          SZ_ERROR_MEM         - Memory allocation arror
          SZ_ERROR_UNSUPPORTED - Unsupported properties
          SZ_ERROR_INPUT_EOF   - it needs more bytes in input buffer (src)
        */

        public static SRes LzmaUncompress(
            P<byte> dest, ref long destLen,
            P<byte> src, ref long srcLen,
            P<byte> props, long propsSize)
        {
            ELzmaStatus status;
            return CLzmaDec.LzmaDecode(dest, ref destLen, src, ref srcLen, props, (uint)propsSize, ELzmaFinishMode.LZMA_FINISH_ANY, out status, ISzAlloc.SmallAlloc);
        }
    }
}
